Micromagnetic Studies of Magnetization Dynamics in Materials for Heat-Assisted Magnetic Recording

Abstract

This dissertation investigates fundamental physical mechanisms and modeling strategies to advance heat-assisted magnetic recording (HAMR) technology. Four studies are presented. The first explores pulsed-laser recording as an alternative to continuous-laser heating, demonstrating that optimized time constants, peak temperature, pulse timing, and thermal gradients can enhance recording performance. The second develops an analytical framework to evaluate Gilbert damping based on the three-magnon scattering model, showing that this mechanism accounts for roughly 80% of the total damping near the Curie temperature. The third study uses micromagnetic simulations to detect in-plane magnetization induced by MgO grain boundaries in FePt media. A novel 45° magnetoresistive read head enables the identification of such noise sources through the asymmetric distribution of magnetization along the cross-track direction. The final part formulates a wavevector-dependent thermal noise model incorporating magnon–phonon coupling, linking microscopic spin–lattice interactions to macroscopic magnetization dynamics. Collectively, these works clarify how thermal, magnetic, and lattice effects influence HAMR performance and provide practical approaches for next-generation magnetic storage design.